Such piston IC engines are described for instance in the German Gebrauchsmuster 90 02 335 and 90 13 928 and furthermore in the post-published, earlier application P 42 18 847.4.
One or more expansion chambers are provided in such piston IC engines and are fed with air compressed to ignition pressure and with fuel at the time of onset of expansion. The expansion chambers drive at least one separate compression chamber delivering the necessary compressed air at the required pressure, the compressed air being controlled by a transfer device and fed at the right time into the expansion chambers. Valves, for instance, are provided as the control means. Illustratively injection nozzles are provided for the fuel feed and inject directly into the expansion chambers or into the compressed-air feed tubes. Moreover, ignition devices are present for the preferred Otto- or gasoline-engine cycle in the expansion chambers.
If for instance such piston IC engines are operated in irregular modes, for instance in cars in city-traffic, then the known drawbacks of IC engines, especially of gasoline engines, will be incurred. Partial-load operation is predominant, during which excess compression takes place, and efficiency is low as a result. During frequent and brief accelerations, for instance when starting from a stop, unfavorable engine operating conditions apply, with incomplete combustion and high emissions of exhaust gases that cannot be fully controlled even using purifying techniques.